C# Programming

Course 419

C# Programming

G419/CN/E.1/609/D.1

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Introduction and Overview

Course Objectives

 In this course, we will discuss the syntax and semantics of C# as

• An object-oriented language
◦ Using encapsulation, inheritance, interfaces, realization, polymorphism, associations, and aggregates
• A component-oriented language focusing on reuse via the .NET Framework
Library, including

◦ Desktop graphical and web-based user interfaces ◦ Enabling cross-language operation ◦ Performing I/O using serial streams and serialization ◦ Interfacing to legacy COM components

• A data-oriented language
◦ Using LINQ and the Entity Framework

COM = component object model I/O = input/output LINQ = Language Integrated Query

Intro-2

Course Contents

Introduction and Overview
Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8 Chapter 9 Chapter 10
Overview and Development Environment From Your Language to C# User Interface Development Defining User-Written Data Types The .NET Framework Interfaces and Polymorphism Writing .NET Components Accessing Databases Other C# Features Course Summary Next Steps

Intro-3

Course Contents

Appendix A Appendix B Appendix C
Performance Tips Unsafe Features Other C# Features

Intro-4

Prerequisites

 Although this course is an introduction to C#, it is intended for

experienced programmers

• A background in a modern procedural language is needed
◦ For example: C/C++, Java, VB, VB.NET, Pascal
• You will need to be comfortably familiar with concepts such as

◦ Data types, variables, declarations, conditionals, loops, expressions, functions, parameter passing, and procedural language flow

 Course 502, Programming With .NET Introduction, is recommended if you have only

• HTML or SQL experience • Experience in languages like COBOL, RPG, PL/SQL, T-SQL

 Some modest exposure to object-oriented concepts is also assumed

Please notify your instructor if you do not meet the prerequisites

COBOL = common business-oriented language HTML = hypertext markup language PL/SQL = procedural language/structured query language
SQL = structured query language T-SQL = Transact-SQL VB = Visual Basic

Intro-5

Course Fonts and Icons

 These fonts and symbols have special meaning in the Course Notes:

• Text in Century Schoolbook italic introduces a new concept or term • Text in Courier bold is C# code keywords or command text • Text in plain Courieris program output or C# code • Text in Courier italic is nonliteral code or command text

Slippery When Wet
Question

Potentially confusing or variance from common use in other languages
Question for the attendee

Surfer
Warning

Additional information can be found at this web reference
Feature that if used incorrectly can lead to problems

Version n
Crystal Ball

This feature is available only in C# version n or later. For example, the note below would indicate that the capability discussed requires at least C# V6
Reference to material that will be discussed later

Good Idea

Feature to make programs easier to write or maintain

Intro-6

Chapter 1

Overview and Development
Environment

Chapter Objectives

In this chapter, we will examine  A brief history of C#  Some elementary features of the language  How to use our development tools

1-2

Chapter Contents

 Evolution From C to C#

• Development Environment • Hands-On Exercise 1.1 • Review Questions

1-3

Differences and Similarities

 C# has borrowed many concepts and constructs from other languages

• In particular, C++, Java, VB, and SQL

 Depending on your background, some aspects of C# might seem the same as a language you have previously used, but …

Don’t be fooled!

• In the midst of the familiar, there will often be some unexpected differences

 The course is written with these differences and similarities in mind

1-4

C-Style Syntax

 It all started with C

• Dennis Ritchie at Bell Labs in 1971 • The language of choice on UNIX and PCs in the 1970s and 1980s
◦ Still widely used

 C introduced what is now called C-style syntax

• Each statement ends in a semicolon (;) • Code blocks (body) are enclosed between {and } • Uppercase and lowercase are distinct • Function-oriented; e.g., mainand printf

#include <stdio.h> int main(void)

{printf("Hello world!\n");

return 0;

}

1-5

C-Style Syntax

 C-style syntax is free-format

• Input is broken into tokens by the compiler • The order of the tokens is important, but not their column positions

 For example, these programs are semantically identical:

int

main(

int main(void)

{

void

) { printf ("Hello World\n")

; return

0; } printf("Hello World\n");

return 0;

}

int main(void) {printf("Hello World\n"); return 0;}

Good engineering practice suggests adopting a clear, properly indented, consistent coding style

• This course demonstrates the generally accepted Microsoft coding style

1-6

Evolution From C

 The C language eventually evolved into other languages with similar syntax, such as C++

• Which added object orientation

… and then Java

• Which was more portable and easier to program than C++
◦ But with reduced performance

… and then JavaScript (JScript)

• For scripting and web niches

… and then …

1-7

C# History

 C# appeared in 2001 as the “first 21st-century language”

• Developed by Microsoft for its .NET initiative • Follows the C/C++/Java trend
◦ But also borrows from Visual Basic, Smalltalk, Lisp, and others

 Designed to be

• Easier to write and much less error-prone than C++ • More efficient with better performance than Java • Multimission—to be used for virtually any kind of application • Multilayer—to be the language of choice in any application layer

 C# is

• Object-Oriented (OO), supporting all modern OO concepts • Component-Oriented (CO), with CO features built into the language • Data-oriented, with SQL-like data-manipulation built into the language

◦ Called Language INtegrated Query (LINQ)

1-8

C# Versions and Standards

 C# is not Microsoft’s language per se

• Standardized through ECMA and ISO/IEC

 Microsoft version is called Visual C# .NET^®

• February 2002: V1—pre-standard version had most language features
• November 2005: V2—fully compliant with 23270 1st edition • December 2007: V3—fully compliant with ECMA-344 4th edition • April 2010: V4—fully compliant, adds extended features • August 2012: V5—fully compliant, adds extended features • July 2015: V6—fully compliant, adds numerous small, very useful features

ECMA = European Computer Manufacturers Association IEC = International Electrotechnical Commission
ISO = International Organization for Standardization

1-9

Hello World in C#

 Here is the “Hello World” program in C#:

using System; public class HelloWorld

{

public static int Main()

{
Console.Write("Hello world!\n");

return 0;

}
}

 Syntax is similar and output is identical to previous C program

• Mainmethod (function) is in a class

• Uses Console.Writemethod from the .NET framework library • Otherwise, it has mostly the same tokens and keywords